A conventional type of technique to detect a relative positional relationship between a vehicle and a pedestrian includes a terminal positioning system that uses an on-vehicle camera to detect a relative position of a pedestrian as disclosed in, for example, Patent Literature 1. Information on a relative position of the pedestrian obtained by the on-vehicle camera is transmitted together with information on the position of the vehicle based on a GPS (global positioning system) to a mobile terminal and used to enhance the accuracy of the positional information in the mobile terminal.